Trigger 7: TBI and cells of the brain

Question 1

name the glial cells of the CNS

Answer 1

astrocytes

microglia

oligodendrites

ependymal cells

Question 2

name the glial cells of the PNS

Answer 2

satellite cells

schwann cells

Question 3

two types of glia

Answer 3

PNS and CNS

Question 4

how much of the brain volume do glia make up

Answer 4

70%

Question 5

why do glial cells make up 70% of the brain volume

Answer 5

huge amount of cells needed to support neurones

Question 6

half of all glia are

Answer 6

astrocytes

Question 7

role of glia cells

Answer 7

• clear out substances that shouldn’t be there - maintaining neurones - maintaining tight junctions

Question 8

support cells of the CNS

Answer 8

astrocytes microglia

Question 9

glial scar formation

Answer 9

A structural formation of reactive glia around an area of severe tissue damage. Caused by Myelin-associated inhibitors, astrocytes, oligodendrocytes, oligodendrocyte precursors and microglia

Question 10

what causes glial scar formation

Answer 10

a response to tissue damage - myelin-associated inhibitors -astrocytes -oligodendrocytes - oligodendrocyte precursors - microglia

Question 11

NG2 GLIA

Answer 11

polydendrocytes

Question 12

NG2 GLIA cause

Answer 12

inhibition of axon regeneration by both expression of inhibitory:

• H2 proteoglycan
• As well as formation of synaptic contacts

Question 13

outline simple steps of glial scar formation

Answer 13

1) Increase homeostatic and tropic functions of glial cells
2) Secretory activity e.g. cytokines and GF of glial cell
3) Proliferation of glial cells
4) Migration of glial cells
5) Glial scar formation and BBB repair

Question 14

the BBB

Answer 14

BBB forms in blood vessels which surrounds most of the brain. Maintains tight junctions of endothelial cells ensuring the brain maintains its highly restricted environment

Question 15

why is BBB important

Answer 15

prevents toxins and pathogens from entering the brain

Question 16

the BBB is highly selective allowing

Answer 16

water, oxygen and LIPID SOLUBLE substances to pass through

Question 17

how is glucose transported into the brain

Answer 17

actively transported

Question 18

tight junction restrict

Answer 18

the space between endothelial cells

Question 19

which glial cell supports the BB by surrounding blood vessels

Answer 19

astrocytic ends (think of picture

Question 20

in a capillary there are…. between endothelial cells

Answer 20

fenestrations (gaps)

Question 21

transcellular lipophilic pathway

Answer 21

lipid soluble agents diffuse through

glucose, amino acids and nucleosides are actively transported across the membrane

Question 22

receptor mediated trancytosis

Answer 22

insulin transferrin

Question 23

adsoprtive transcytosis

Answer 23

albumin and other plasma proteis (forms vesicle in outer membrane which cross the memrane to the other side

Question 24

paracellular aqueous pathway

Answer 24

means water can still pass through tight junctions

Question 25

astrocytes

Answer 25

surround blood vessels in the brain, helping to maintain tight junctions - processes make cotnact with the BBB - provide nutirents to the neurones by creating an interface to the blood

Question 26

amoeboid astrocytes

Answer 26

acute disease phagocytosing- mops up damaged cells

Question 27

Astrocytes can take two forms

Answer 27

rod-like amoeboid

Question 28

rod-like astrocyte shape

Answer 28

Chronic disease Lays down layer of rods

Question 29

how do astrocytes support synapes

Answer 29

by recyling NT via retrograde signalling

Question 30

microglia

Answer 30

survey for foreign obects, acting like macrophages (clear cellular debris and neurones using autophagy)

Question 31

how do microglia help organise the brain

Answer 31

by destroying debris and unneeded neurones using autophagy

Question 32

In TBI, receptors on microglia bind with

Answer 32

APoE (CTE)

Question 33

microglia promote

Answer 33

inflammation

Question 34

resting shape of microglia

Answer 34

ramified

Question 35

ramified microglia

Answer 35

act as surveillance cells to maintain the homeostasis of the neuronal microenvironement -directly remove dysfunction synaptic terminals to maintain the integrity of neuronal circuitry

Question 36

rod-shaped/ bipolar microglia

Answer 36

have elongated cell bodies with their processes extended towards the two ends - phagocytic in nature which involve the internalisatio of degenerating neurons after CNS injury - invovled in neuronal circuit regorganisation via synaptic stripping

Question 37

amoeboid microglia

Answer 37

- highly motile with few processes - invole int ehe degradation of extracellula laminin - acitvely pahgocytes cellular debrs and extrceullar protein aggregates such as B-amyloid and alpha-synuclein - secrete neurotoxic factors which induce neruone cell death

Question 38

which form of microglia cause neuronal cell death

Answer 38

amoeboid microglia by secreting pro-inflammatory cytokine (IL-1B, TNFa, NO etc)

Question 39

in a healthy CNS how are microglia displayed

Answer 39

as ramified microglia

Question 40

in response to TBI, chronic neuroinflammation, LPS and bacteria-induced neuroinflamamtion etc ramified microglia change to

Answer 40

ameoboid microglia

Question 41

LPS activation and chronic and sustained activation of microglia in later stages of neurodegeneration convert rod-shape microglia to

Answer 41

ameoboid microglia

Question 42

scratched laminin-coated surgave, patients with paralytic dementia and chronic neuropathological disorders causes the conversion of ramified microglia to

Answer 42

rod-shaped

Question 43

rod-like microglia are present into what sort of disease

Answer 43

chronic e.g. degenrative brain disorders

Question 44

amoeboid microglia are present during.... disease

Answer 44

acute disease

Question 45

when a micrgolia senses danger

Answer 45

* It becomes more compact, with the long arms contract inwards (ameboid). * These microglia then start to multiply rapidly. * They release cytokines to attract other immune cells, like T cells * Also release chemicals which recruits neurones and astrocytes which helps the brain heal

Question 46

three main types of microglia 9accoridng to loacation

Answer 46

cortex-ramified corpus callosum hippocampus

Question 47

the gliovascuar unit

Answer 47

the BBB and glia (astroctyes and microglia) surrrounding it

Question 48

the gliovascular unit explanation

Answer 48

The BBB and the astrocytes surrounding it- the receptors which go within that membrane to cause movement of ions such as TGF-B and other cytokines, glutamate transmitters. Further surrounding this complex are microglia- ensure what goes in and out of the brain

Question 49

within TBI patients

Answer 49

both immediate and delayed dysfunction of the BBB/gliovasuclar unit are observed

Question 50

how is the BBB disrupted during TBI

Answer 50

disruption of tight junctions increases permebaility * oxidative stress * increased production of pro inflammatory mediators * upregulation of cell adhesion molecules expression on the surface of the brain endotheliumàpromoting influx of inflammatory cell